Inorganic microporous solids such as zeolite (i.e., aluminosilicates) are particularly suitable to be used as molecular sieves, sorbents, or ion exchange materials because of their rigidity, stability, and large internal surface area. Organometallic analogs of zeolite can be tailor-made so as to confer properties not available in their inorganic counterparts, thereby expanding their applications as catalysts or components of biosensors. However, organometallic zeolite is generally fragile and heat-unstable. Thus, there exists a need for a robust organometallic zeolite with desired properties.
An aspect of this invention relates to an organometallic zeolite formed of a multiplicity of units, each of which is of formula (I):
(X.M)mxe2x80x83xe2x80x83(I)
M is a metal ion (e.g., Co2+ or Mn2+). X is a cyclic ligand (e.g., porphine or phthalocyanine) which coordinates to the metal ion to form an X.M and is substituted with at least two linking groups (e.g., 4-pyridyl) and optionally with one or more non-linking groups (e.g., 4-pyridyl or phenyl). Each linking group contains a lone pair of electrons for coordination to a metal ion. Each of the non-linking groups, independently, is aryl, heteroaryl, aralkyl, or heteroaralkyl, optionally substituted with alkyl, alkoxy, hydroxyl, hydroxylalkyl, carboxyl, halo, haloalkyl, amino, aminoalkyl, thio, thioalkyl, alkylcarbonyloxy, alkyloxycarbonyl, alkylcarbonyl, alkylcarbonylamino, aminocarbonyl, alkylsulfonylamino, aminosulfonyl, boronic acid, sulfonic acid, or alkylsulfonyl. m is an integer which ranges from 4 to 12. The zeolite of this invention also has the following features: (1) each (X.M)m forms a ring-shaped structure with a pore of an interior diameter of 10 to 25 xc3x85; (2) the non-linking group of each X.M, if present, is located inside a pore; (3) the linking group of each X.M coordinates to the metal ion of a neighboring X.M and the metal ion of each X.M further coordinates to a linking group of a neighboring X.M; and (4) each (X.M)m shares an X.M with each of its neighboring (X.M)m.
Note that the just-described network of (X.M)m is a layer. A multiplicity of such layers stack together to form a zeolite of this invention. The pores of each layer are aligned to form channels perpendicular to the plane of the layers.
A salt of the above-described zeolite is also within the scope of this invention. For example, a salt can be formed between a negatively charged substituent of a non-linking group of X.M (e.g., carboxyl) and an alkali metal ion (e.g., a sodium ion or a potassium ion); an alkaline earth metal ion (e.g., a magnesium ion or a calcium ion); an ammonium ion (NH4+); or an organic ammonium group (e.g., tetramethylammonium ion or diisopropylethylammonium ion). As another example, if an amino group is present on a non-linking group, it can form a salt with a negatively charged counterion. Suitable counterions include, but are not limited to, chloride, hydrochloride, bromide, iodide, sulfate, nitrate, phosphate, or acetate.
Set forth below are some examples of X.M: cobalt(II) 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine; manganese(II) 5,15-di(4-pyridyl)-10,20-di(4-aminophenyl)-21H,23H-porphyrin, and manganese(II) (5,15-di(4-pyridyl)-10,20-di(4-hydroxyphenyl)-21H,23H-porphyrin).
As used herein, alkyl is a straight or branched hydrocarbon chain containing 1 to 8 carbon atoms. Examples of alkyl include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-methylhexyl, and n-octyl.
By cycloalkyl is meant a cyclic alkyl group containing 3 to 8 carbon atoms. Some examples of cycloalkyl are cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, adamantyl, and norbornyl. Heterocycloalkyl is a cycloalkyl group containing 1-3 heteroatoms such as nitrogen, oxygen, or sulfur. Examples of heterocycloalkyl include piperidinyl, piperazinyl, tetrahydropyranyl, tetrahydrofuryl, and morpholinyl.
Aryl is an aromatic group containing 6-12 ring atoms and can contain fused rings, which may be saturated, unsaturated, or aromatic. Examples of an aryl group include phenyl, naphthyl, biphenyl, phenanthryl, and anthracyl. Heteroaryl is aryl containing 1-3 heteroatoms such as nitrogen, oxygen, or sulfur and can contain fused rings. Some examples of heteroaryl are pyridyl, furanyl, pyrrolyl, thienyl, thiazolyl, oxazolyl, imidazolyl, indolyl, benzofuranyl, and benzthiazolyl.
Aralkyl refers to a moiety which contains both an alkyl group and an aryl group. By the same token, heteroaralkyl refers to a moiety containing both an alkyl group and a heteroaryl group.
Note that an amino group can be unsubstituted, mono-substituted, or di-substituted. It can be substituted with groups such as alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, or heteroaralkyl. Halo refers to fluoro, chloro, bromo, or iodo.
Other features or advantages of the present invention will be apparent from the following detailed description of several embodiments, and also from the appending claims.